Editor's note: There is a lot of confusion, misinformation, stigma, and bias about how your weight impacts your health. So we’ve created a comprehensive review and critical analysis of the science on weight and health as a resource. We get very in the weeds here, so we’ve broken it up into four parts:

- Part One: A Bit About BMI

- Part Two: What We Know About Weight and Health

- Part Three: What We Don't Know

- Part Four: What to Do With All This Information

If you’re looking for a TL;DR version, here are the main takeaways: Weight is a marker of health, but it’s not the only one. While we know that excess weight is associated with certain health conditions, we don’t always know why. To that end, prescribing weight loss as a solution to mitigate health risks can often be ineffective and even harmful—a more effective approach might be to focus on behavior changes (like exercise, healthy eating, and so on) over modifying a physical attribute. Most importantly, while weight can be an important piece of information, it isn’t the conclusive measure of your wellbeing, your life, or your worth. Having excess weight is not a moral failing, and it’s dangerous and cruel to treat it like one.

This long list of ailments associated with obesity—along with the fact that, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) approximately 70 percent of the adult population in the U.S. is overweight or obese—has led to decades of news stories and reports surrounding our “obesity epidemic.” (Not to mention, the foundation of several capitalistic industries predicated on our need to fit our bodies into specific, sometimes unattainable parameters of weight and shape.)

The research, which we’ll dive into in a bit, confirms these associations and some direct links between increased weight and certain health risks. But when it comes to why people of larger sizes are at increased risk for various health conditions, the research is often less clear. And no matter how much information we have about weight as a marker of health, it doesn’t always give us specific answers about how best to mitigate health risks. Just because excess weight is in fact associated with increased health risks doesn’t necessarily mean that focusing solely on weight loss is the best solution.

To give you more information about where these associations originate and what they may mean for you, we spoke with several researchers who specialize in endocrinology, physiology, and weight management to walk us through it. Is it possible that the science behind the headlines tells a much more complicated story—one that suggests these stigmatizing messages about your weight may be oversimplified and, at times, even dangerous?

Part One: A Bit About BMI

Most of the research on weight and health relies on body mass index (BMI) to categorize people based on weight.

Your BMI is calculated by taking your weight in kilograms and dividing it by your height in meters squared. A “normal” or “healthy weight” BMI is one that’s between 18.5 and 24.9. Any number below that is considered “underweight.” At 25 and above, you’ll get into “overweight” territory, and once you hit 30, you’re considered “obese.”

Researchers use BMI because it’s easy and, in many cases, free, Michael D. Jensen, M.D., professor of medicine in the department of endocrinology at the Mayo Clinic and co-chair of the National Health Institute’s (NIH) expert panel on obesity, tells SELF.

BMI is particularly useful for looking at large groups of people to identify trends, which researchers often then examine in further detail using additional markers of health, such as blood pressure, Dr. Jensen says. So, when we get into the research on weight and health, you’ll notice BMI used a lot.

The thing is, we know that BMI is an imperfect measure of health. Research shows that you can have an obese BMI and be metabolically healthy, and you can have a normal BMI and be metabolically unhealthy.

BMI may be an easy way to categorize weight in population-based studies, but it’s not a great way to assess an individual’s health risk without digging further. It doesn’t take into consideration things like muscle mass, body fat percentage, or where and how your body stores fat.

One of the studies to show just how imperfect BMI is on a large scale was published in 2008 in JAMA Internal Medicine, in which researchers found that BMI didn’t always correlate with other measures of health. For the study, researchers at the Albert Einstein College of Medicine used health data from 5,440 participants, originally collected between 1999 and 2004 as part of the CDC’s National Health and Nutrition Examination Surveys, a long-running nationally representative population survey.

Along with BMI, they looked at data for blood pressure, cholesterol levels, fasting glucose levels (often used as a marker of insulin resistance), and high sensitivity C-reactive protein (used as a marker of inflammation). Participants were sorted into categories based on BMI (normal, overweight, obese) and cardiometabolic health.

Results showed that, although BMI correlated with metabolic health, there were exceptions. Among women, 78.9 percent of those with normal BMIs, 57 percent of those with overweight BMIs, and 35.4 percent of those with obese BMIs were metabolically healthy. Conversely, 21.1 percent of those with normal BMIs, 43 percent of those with overweight BMIs, and 64.6 percent of those with obese BMIs were metabolically unhealthy.

“These data show that a considerable proportion of overweight and obese U.S. adults are metabolically healthy,” the authors conclude, “whereas a considerable proportion of normal-weight adults express a clustering of cardiometabolic abnormalities.” Furthermore, the observed results, along with other data at the time, led to the “increasing recognition that the disease risks associated with obesity may not be uniform.”

Another study, published in the International Journal of Obesity in 2016, found similar results using data from the National Health and Nutrition Examination Surveys between 2005 and 2012. Here, researchers included data for more than 40,000 participants and they found that almost half of those with BMIs in the overweight range and 29 percent of those in the obese range were considered metabolically healthy. Conversely, more than 30 percent of those in the normal range were considered cardiometabolically unhealthy.

“Weight, though it is a piece of information, does not by itself indicate the presence or absence of health,” Yoni Freedhoff, M.D., founder and medical director at the Bariatric Medical Institute in Ontario, Canada, tells SELF. “Plenty of really thin people are living horribly unhealthy lives, and [there are] people who might be quite a bit overweight as far as some table or scale would suggest who live very healthfully.”

One crucial factor that BMI doesn’t account for is the type and location of fat on your body.

You’re stuck with basically the same amount of fat cells your entire adult life—you lose and replace about the same amount every year (roughly 10 percent). So losing or gaining weight doesn’t mean losing or gaining fat cells, it means shrinking or growing the ones you already have. (Although a 2012 study on overfeeding and fat cells in the upper versus lower body suggested this may be more complicated than we think, because fat cells in the legs don’t seem to react to weight gain and loss the same way as abdominal fat does.)

And having fat, it turns out, is crucial to your overall health. Aside from insulating your body for temperature regulation and cushioning your organs and bones from injury, fat is actually pretty busy. Fat cells also play a role in your immune system, in regulating the level of several hormones in the body (including estrogen), and energy metabolism. But, as with anything else in the body, there’s a possibility for the careful balance of these systems to be thrown out of whack.

Importantly, BMI doesn’t account for the presence of what’s called visceral fat, which sits deeper under your skin and surrounds your internal organs. Unlike subcutaneous fat (also referred to as white fat), which tends to settle around the hips and thighs, visceral fat tends to increase your waist circumference.

Research suggests that visceral fat is more likely to contribute to an increased risk for heart disease and type 2 diabetes. A study published in 2004 in Endocrinology found that, compared to subcutaneous fat, visceral fat released more vascular endothelial growth factor (a protein involved in the formation of blood vessels), interleukin-6 (a cytokine involved in inflammation signaling), and plasminogen activator inhibitor type 1 (a protein involved in blood clotting and usually released as a result of inflammation). Together, this and other current research suggests that visceral fat in your belly is more actively involved in promoting inflammation than subcutaneous fat, and is potentially more of a health risk than other types of body fat.

So, keep in mind that as we discuss BMI as it relates to disease risk, it’s important to remember that there’s a lot we still can’t infer from that measure, and certainly not from that measure alone. However, when it comes to studying weight’s effects on health at the population level, it’s still a useful first step.

Part Two: What We Know About Weight and Health

It can be frustrating to look at a list of negative health implications tied to weight without knowing anything about those associations. So we’ve identified a few of the conditions that research has repeatedly found are associated with obesity, as well as any context about the biological mechanism behind that association when possible.

When we look at the research on weight and health implications, there are four main trends that we see, according to Dr. Jensen, who co-chaired the 2013 NIH evidence review on managing obesity. They essentially boil down to: the way excess fat affects other bodily functions (like moving, breathing, etc.); how and where our body stores fat—and how that relates to disease; how body fat relates to inflammation; and how fat impacts hormone levels in your body

These trends help us better understand the associations between weight and health, but they don’t present the complete picture, nor do they always help us draw definitive conclusions about why many people with higher BMIs are at a greater risk for these conditions.

Below, you’ll find some of the research about health conditions commonly associated with obesity. Although it’s not an exhaustive list of studies, it represents, in general, what we know and don’t know about these associations.

Osteoarthritis

Some health conditions seem to be associated with increased weight in “mechanical” ways, which may be the case with osteoarthritis, sleep apnea, and gastroesophageal reflux disease. Here, researchers suspect that excess weight is directly affecting the ability of the joints, lungs, and gastrointestinal system to do their jobs.

And the CDC lists excess weight as one of the major modifiable risk factors for developing arthritis, along with joint injuries, infections, occupational hazards, and smoking.

According to a 2015 meta-analysis in BMJ Open, having a BMI in the overweight or obese range can significantly increase your risk for knee osteoarthritis. Researchers analyzed results from 14 previous studies and found that those who had an overweight BMI had 2.5 times the risk for osteoarthritis compared to those with a normal BMI, while those with an obese BMI had 4.6 times the risk for knee osteoarthritis. However, the analysis included a relatively small number of studies, many of which had a relatively small number of participants.

Sleep Apnea

Sleep apnea is another condition in which the research shows a strong association to increased weight (and an increased risk of heart disease—more on that later). According to clinical guidelines for diagnosing and managing obstructive sleep apnea released by the American Academy of Sleep Medicine in 2009, having a BMI over 35 is enough to put you at high risk for having sleep apnea, and the presence of obesity at all merits investigation into the presence of sleep apnea.

Just over 26 percent of Americans between the ages of 30 and 70 are estimated to have sleep apnea (men have double the rate of women), according to data for 1,520 participants published in 2013 in the American Journal of Epidemiology; and sleep apnea rates have been rising steadily over the last two decades. Among those with an obese BMI, around 40 percent of men and 3 percent of women have sleep apnea, according to a small but oft-cited study in JAMA Internal Medicine. And, in a study of 290 people undergoing weight-loss surgery, over 70 percent of them had sleep apnea.

However, exactly how excess weight directly causes or worsens existing sleep apnea isn’t completely understood. One proposed mechanism, as outlined in a review published in 2008 in the Proceedings of the American Thoracic Society, is that fat that sits around the neck and upper airways can contribute to the collapsing of those airways during sleep. The idea comes from data showing that, in general, as BMI increases, so does the severity of sleep apnea.

To what degree weight loss is an effective treatment for sleep apnea isn’t totally clear. A study published in Sleep in 2013 looked at the results from seven previous studies and found that weight loss achieved through diet and exercise could improve patients’ scores on the apnea-hypopnea index (a measure of the amount of decreases in blood oxygen levels during sleep, which indicates the severity of sleep apnea), but it wasn’t enough to fully treat their symptoms. On the other hand, a large meta-analysis from 2004 that was published in JAMA looking at the effects of bariatric surgery in the results from 136 previous studies confirmed that, yes, bariatric surgery helps patients lose weight, and symptoms of sleep apnea were either improved or resolved in 83.6 percent of patients.

So, although the mechanical effects of excess weight seem obvious in this case, the research suggests that they’re fairly complex, and weight loss on its own isn’t necessarily enough to treat sleep apnea in every patient.

Type 2 Diabetes

A 2014 meta-analysis published in Obesity Reviews confirms there is a correlation between obese BMI and type 2 diabetes risk, even among those considered otherwise metabolically healthy. After going through over 1,000 studies involving BMI and type 2 diabetes incidence, only seven met the researchers’ criteria for inclusion so they supplemented that data with data from the English Longitudinal Study of Aging. But, looking at the results of all those studies, which included data for 1,770 participants and 98 cases of type 2 diabetes, the researchers found that metabolically healthy people with obese BMIs still had double the risk for developing type 2 diabetes compared with metabolically healthy people with normal BMIs.

The relationship between type 2 diabetes and obesity is somewhat unique in that doctors generally agree that losing a specific proportion of body weight (around five to 10 percent) may be beneficial in preventing or delaying the onset of the condition. In fact, the NIDDK specifically recommends that people who are at a high risk for developing type 2 diabetes can “prevent or delay” its onset by losing between 5 and 7 percent of their starting weight.

So where does that claim come from? Dr. Jensen specifically points to research from the Diabetes Prevention Program, a series of studies that began in 1996. The DDP is one of the longest-running studies on the relationship between weight and diabetes risk and was sponsored by the NIDDK. The initial trials included 3,234 participants recruited from 27 clinical centers around the country. All participants were deemed to be at high risk for diabetes before entering the study based on their elevated fasting glucose levels. They were randomly assigned to be in one of three groups: One that took the drug metformin, (commonly used to control blood glucose levels in patients with type 2 diabetes) and received standard advice about physical activity and diet, another that received a placebo and the same standard advice, and a third lifestyle change group that was specifically designed to help participants lose 7 percent of their body weight via a careful diet, 150 minutes of exercise per week, and individual check-ins.

After three years, those in the lifestyle change group had a 58 percent lower chance of developing type 2 diabetes compared to those in the placebo group. Those in the metformin group had a 31 percent lower chance of developing the condition compared to the placebo group. The lifestyle changes proved to be especially effective for people older than 60, while metformin was especially helpful for those between the ages of 25 and 44 as well as those with a BMI over 35. These trends held up even after they followed the groups over 15 years.

So, for those who are already at risk for type 2 diabetes, losing weight—or participating in lifestyle changes that may lead to weight loss—can be beneficial, according to these results.

But why is a higher BMI associated with type 2 diabetes? While that’s not fully understood, some research suggests it may have to do with how and where your body stores fat, and how that relates to energy storage in the body.

Normally, your pancreas produces the insulin required to process the sugar (glucose) in your food so that it can be stored in your liver, muscles, and fat tissue. In people who have developed insulin resistance, this pathway doesn’t work the way it’s supposed to: Your liver, muscles, and fat tissue aren’t able to take in glucose as efficiently as they used to, so your body has to make more insulin to compensate. For some people, insulin resistance eventually leads to prediabetes and type 2 diabetes as the pancreas can’t make enough insulin to keep blood glucose in the normal range, meaning extra glucose stays in your bloodstream.

Fat cells, which store fat and glucose to be later used as energy, are an incredibly important part of this whole process, Dr. Jensen explains. But the exact way an excess amount of fat contributes to insulin resistance isn’t totally understood. Research also shows that visceral fat is associated with higher levels of inflammation signaling in the body (more on that later), but again it’s not clear that fat itself is causing that increase.

Cardiovascular Disease

There is some evidence to suggest that having excess fat may contribute to chronically high levels of inflammation in the body, fueling an increased risk for health issues such as cardiovascular disease. Indeed, the American Heart Association says that obesity raises your risk for heart disease and stroke, partly by increasing your blood pressure, throwing off your cholesterol levels, and increasing the risk for type 2 diabetes.

In general, inflammation is actually a good thing. It’s a sign that your body’s immune system is reacting to a specific danger, such as swelling around a sprained ankle or cut, or causing a fever with the flu, and doing its job. But, when inflammation continues on a low level for an extended period of time, it can be harmful to your body, and especially hard on your blood vessels. The current thinking is that inflammation helps lead to a buildup of plaque within the blood vessels which the body attempt to wall off from the flow of blood. But if the wall breaks, the plaque inside it ruptures and mixes with blood, causing the blood to clot, leading to a heart attack or stroke.

Several health markers are known to increase the risk of cardiovascular disease. In a meta-analysis published in 2010 in the Journal of the American College of Cardiology, researchers looked at the correlation between cardiovascular disease and metabolic syndrome, which is related to both obesity and type 2 diabetes and defined as having at least three of five risk factors, including specific waist circumference measurements, fasting glucose level, cholesterol level, triglyceride level, or high blood pressure. They analyzed the results from 87 previous studies, including data for over 951,000 patients, and found that having metabolic syndrome was a significant risk factor for developing cardiovascular disease, even if participants hadn’t developed type 2 diabetes, and metabolic syndrome was associated with an increased risk of death from any cause. These findings suggest that the health markers that make up metabolic syndrome together can increase your risk of cardiovascular disease, even in the absence of type 2 diabetes.

More recently, a meta-analysis published in Circulation in 2016 examined the relationship between BMI, fat located around the abdomen, heart failure, and mortality in 28 previous studies. They found that BMI and heart disease risk were highly correlated such that, an increase in BMI by five units increased participants’ risk for heart failure by about 41 percent and their risk for death from heart failure by 26 percent.

But the link between BMI and inflammation isn’t totally understood. There is research to suggest that people with higher BMIs have higher levels of C-reactive protein, a common marker of inflammation. And other research suggests that people who have high levels of C-reactive protein have a higher risk for a future heart attack. But whether or not that inflammation is directly caused by excess fat hasn’t been proven, Dr. Jensen says.

That’s partly due to the fact that the test most commonly used to detect inflammation looks for protein markers (including C-reactive protein) in blood, but it’s an “incredibly nonspecific” measure, Dr. Jensen says, meaning we don’t know if elevated levels of those inflammatory proteins are coming from fat tissue. “I couldn’t find one study that actually proved in humans that the inflammation in the blood was actually coming from adipose tissue,” he says.

Again, although weight is related to (and may have a direct impact on) heart health, it’s not the only factor at play.

Cancer

According to the National Cancer Institute (NCI), nearly all the research linking obesity to cancer risk comes from observational studies, which means those studies can be challenging to interpret and can’t definitively prove that obesity causes cancer. Yet, there are some consistent findings that indicate obesity is linked with a higher risk for certain types of cancer.

Fat tissue is involved in the production and regulation of hormone levels in your body, which can play a role in the association between weight and certain cancers. Fat cells are involved in the production of a variety of hormones, including leptin (involved in regulating hunger cues), and adiponectin (highly involved in insulin regulation). But the effect that’s best understood is fat tissue’s ability to convert circulating steroids into estrogen via the enzyme aromatase, Dr. Jensen explains.

We know that postmenopausal women with higher BMIs have higher levels of estrogen in their bodies. That’s one reason why, some researchers believe, obesity is correlated with a higher risk for estrogen-related cancers among postmenopausal women, such as breast and endometrial cancers.

This link has been most strongly associated with postmenopausal women who have not used hormone therapy, according to the NCI. For instance, a 2014 meta-analysis published in Epidemiology Reviews looked at the results from 57 previous papers related to BMI and cancer as well as 32 papers related to breast cancer and hormone use. They found that, among postmenopausal women, those with BMIs in the obese range had a higher risk for developing hormone receptor-positive breast cancer compared to those with BMIs in the normal range, especially among those who haven’t used hormone therapy. Interestingly, obesity also seemed to have a protective effect in premenopausal women, reducing the chances of receptor-positive breast cancer in those participants by about 20 percent in this study. (Hormone receptor-positive breast cancer indicates that the breast cancer cells have receptors that attach to the hormones estrogen or progesterone, or both, and depend on these hormones to grow.)

The estrogen piece may explain some of the association between increased weight and increased risk of breast cancer, but the link and risk for other types of cancer may be less clear or direct.

For instance, the risk for esophageal cancer may be fueled by the link between obesity and acid reflux, which we know raises your risk for Barrett’s esophagus, an inflammatory condition that may lead to esophageal cancer (17,290 new cases estimated this year). And the increased risk for gallbladder cancer (12,190 new cases estimated this year) may be affected by the risk for gallbladder disease that comes with obesity.

In these examples, we can see how obesity is a factor associated with these health conditions, but we can also see how other factors can come into play—factors that could affect both weight and disease risk. This furthers the point that, in some cases, obesity undeniably is a risk factor for certain health conditions, but it’s rarely the only one, and, as we’ve seen, it doesn’t necessarily pose the same risk for all individuals.

Overall, research indicates that obesity is a significant factor in a number of cancer cases: A 2012 meta-analysis published in Lancet Oncology found that globally, 3.6 percent of all new cancers that year could be attributable to excess weight. And in just North America, 3.5 percent of total cancers in men that year and 9.4 percent in women could be attributed to obesity. And when looking just at obesity-related cancers (including esophageal, colon, rectal, pancreatic, gallbladder, postmenopausal breast, ovarian, uterine, and kidney cancers) in North America that year, 21 percent of those cancers in men and and 19 percent in women were attributable to excess BMI.

According to a large meta-analysis published in 2016 in Cancer Epidemiology, globally in women, obesity played a role in 43 percent of gallbladder cancers, 37 percent of esophageal cancers, and 25 percent of kidney cancers. (By comparison, smoking was found to be responsible for 62 percent of all larynx cancer cases and 58 percent of all lung cancer cases in women.) The U.S. had the highest proportion of colorectal cancer cases attributable to obesity (35.4 percent in men and 20.8 for women) as well as pancreatic cancer (20 percent for women) and breast cancer (22.6 percent) cases.

Part Three: What We Don't Know

All of the research we’ve covered so far confirms that weight can be identified as a risk factor in many health conditions. And in some cases, there are even theories as to the mechanism of action behind the association. But for others, we're still not sure. And this still doesn't tell us why excess fat raises disease risk for some people and not others.

“The most fascinating thing is that not everybody who gains extra fat suffers the same way,” Dr. Jensen says. “Some people can put on an extra 50 pounds of fat and be almost as healthy as they are when they’re lean, and others can put on 20 or 30 pounds of fat and they’re already getting type 2 diabetes.”

And then there’s what some researchers refer to as the “obesity paradox.”

The "obesity paradox" is the observation that, in some studies, overweight and obesity up to a BMI of 35 is associated with lower risk of death than normal BMIs.

To challenge these assumptions, Bacon cites the “obesity paradox.” This is a term used in research to describe patterns observed in the literature which suggest that, despite being correlated with an increased risk for developing certain diseases, obesity is also correlated with a reduced risk of dying from several of those conditions.

The concept is particularly striking in a meta-analysis published in 2013 in JAMA in which researchers looked at 97 previous studies to correlate mortality rates with BMI. Their data included nearly 2.9 million people and about 270,000 deaths. They did find a higher rate of death from all causes for those with BMIs above 35, but those with BMIs between 30 and 35 (still in the obese range) didn’t show any higher mortality rate compared to those with normal BMIs. In fact, those in the overweight range—with BMIs between 25 and 30—had the lowest mortality rate.

So, although these results suggest there may be some health consequences associated with higher BMIs, they clearly aren’t as cut and dry as many have been led to believe. When it comes to cancer, Dr. Jensen suspects that, although obesity may raise your risk for certain cancers, it may also lower your risk for others.

However, recent research has challenged the idea of the obesity paradox, particularly when looking at cardiovascular disease and death related to cardiovascular disease.

One study, published in April in JAMA Cardiology, included data for 190,672 people collected between 1964 and 2015. Compared to people with normal BMIs, those with overweight and obese BMIs had a greater risk for developing cardiovascular disease, but it gets more complicated from there. Those in the overweight category had a similar risk for mortality compared to those in the normal category. But because of the risk for developing cardiovascular disease, the authors conclude those in the overweight category were living a longer life at the expense of living a greater proportion of their lives with cardiovascular disease. Those in the obese category were more likely to develop and die from cardiovascular disease compared to those in the normal weight category.

Another study, this one published in May in the European Heart Journal, analyzed data for nearly 300,000 people that was collected between 2005 and 2010. They found that the association between BMI and cardiovascular disease may be more susceptible to bias, while the link between excess fat and cardiovascular disease may be worth more investigation. In this study, people with BMIs between 22 and 23 had the lowest risk for cardiovascular disease events (e.g. heart attacks), and those with BMIs of 18.5 or lower (classified as underweight) had a higher risk of cardiovascular disease. As BMI increased beyond 23, the risk for cardiovascular events increased. And with other measures of excess fat, such as waist circumference and body fat percentage, the relationship was more linear: The more excess fat, the higher the cardiovascular risk. However, all of their data came from participants who were white and in the U.K., so we don’t know how these findings would compare to those for people of other ethnicities or in other countries.

We also can’t ignore that mental health may be a significant factor in some associations between weight and health.

People with higher BMIs are more likely to experience weight-based discrimination when applying for jobs, in a courtroom, and at the doctor’s office. And that stigma and the stress it causes may contribute to poorer health.

“Just because we see higher rates of disease among heavier people doesn’t mean that it’s the fat tissue on their body that’s the problem,” Bacon tells SELF. For instance, we know from research on the health effects of racism that being on the receiving end of perceived discrimination can increase psychological stress. And, if unresolved, that can contribute to physiological inflammation.

“The stigma associated with being heavier increases risk for stress, depression, and anxiety—all of which have important implications for long-term physical health,” Jeffrey Hunger, Ph.D., a researcher who studies the health effects of weight stigma at UCLA, tells SELF.

One study published in 2010 in JAMA Psychiatry found that depression and obesity often go hand in hand, and the two conditions may actually fuel each other. The study, a meta-analysis that included data for more than 55,000 participants from 15 previous studies, found that having a BMI in the obese category increased the risk for the onset of depression by 55 percent. And having a diagnosis of clinical depression increased the risk for developing obesity by 58 percent.

Indeed, research suggests that people with mental illnesses, such as depression and anxiety, also have higher levels of C-reactive protein, a marker of inflammation in the body. So mental health issues associated with obesity and weight stigma may be contributing to the higher levels of inflammation seen in people with higher BMIs. And any research that “just looks at the relationship between weight and [physical] health is missing this critical piece,” Hunger says.

Weight bias becomes especially dangerous when it occurs in health care. People of size are less likely to be prescribed certain routine medications (including antibiotics) and more likely to delay or avoid doctor’s appointments, potentially allowing diseases to progress undiagnosed or for warning signs to be missed. For some, that’s because they perceive the doctor’s office to be a source of embarrassment, not valuable care. And, for others, that’s because they don’t want their size to unnecessarily become the focus of yet another appointment. In these ways, weight stigma may have an immeasurable effect on their health.

“By virtue of living in a larger body, somebody is going to have a harder life because people aren’t going to be treating them as well, and that [may] result in higher disease risk,” Bacon says.

Part Four: What to Do With All This Information

Weight is often treated as a “modifiable risk factor,” but it’s not that simple.

Treating it as something that can be adjusted easily for everyone vastly oversimplifies both our views on weight management and the real impact that weight has on disease risk.

As we’ve covered, a higher weight is often associated with increased disease risk, but it’s far from the only factor involved. And while many doctors and researchers and headlines tend to focus on weight as the culprit at the root of disease and, therefore, weight loss as the magic cure-all, it’s not that cut and dry.

For example, a study published in the European Heart Journal in 2013 looked at over 43,000 participants who were originally recruited as part of the Aerobics Center Longitudinal Study in the 1990s. Here, researchers looked at participants’ BMI category and fitness level (measured by a treadmill test) as well as metabolic health markers (such as blood pressure, cholesterol levels, and triglyceride levels).

They found that 30.8 percent of those who had been categorized as obese by their BMI were metabolically healthy, suggesting yet again that BMI on its own is not a direct measure of health. And that group also had better overall fitness scores compared to those with obese BMIs who were not considered metabolically healthy, which underscores the idea that behaviors (like physical fitness) can play a crucial role in health.

“We confuse weight, which is a physical attribute, with behavior, things like exercise and eating,” Bacon says. “And that’s the root of the problem, because then when you’re looking at a physical attribute you end up demonizing people.”

That demonization gives way to fat shaming and all manner of stigmatization. The logic seems to go something like: If your weight is a reflection of your behavior or your health and it’s something that’s in your control, being overweight or obese is a sign of neglect, so you deserve to feel bad about it.

That stigma, unfortunately, can extend to diseases we often associate with weight, like type 2 diabetes or heart disease. In some cases, this can lull people with lower BMIs into a false sense of security about their risks for those conditions, and can also set us up for the practice of concern trolling: shaming people for their weight based on the assumption that they must be unhealthy when, in reality, we know nothing about their health status (nor is it any of our business).

And it’s worth noting that recent research suggests that judging people about their weight doesn’t actually lead them them to lose any weight. Of course, even if it did, that wouldn’t make it OK, but these findings emphasize the fact that weight shaming and concern trolling aren’t really about health or improving anyone’s life—they’re about placing a moral value on a particular size.

“There shouldn’t be any defensiveness about [saying,] ‘Let’s just address health directly and be kind to people," Bacon says. "But to make those kinds of claims, I always [feel like I] have to be on the defensive because the culture is so messed up and the belief systems are so messed up."

Figuring out when and how to focus on weight-loss—if ever—depends on who you ask.

“Really, the goal is not directly weight loss,” Dr. Freedhoff says. “Even in a patient who’s presenting with a weight-responsive condition (such as type 2 diabetes), improving the quality of their diets and quantity of their exercise—these are things that may have benefits whether a patient loses weight or not.”

Dr. Jensen argues that, if done properly, improving diet and increasing physical activity in a patient with obesity should naturally result in weight loss. “Most typically, if you aren’t finding your weight/waist go down, you aren’t following the healthy diet and the activity plan you think you are,” he says.

Still, that doesn’t necessarily mean that weight loss itself needs to be the number one priority—nutrition and exercise have benefits far outside of any weight loss that may occur, such as better quality sleep, improved mental health, and increased fitness level. That’s why Dr. Freedhoff encourages his patients of all weights to find their “best weight,” which is the weight you’re at when you’re living “the healthiest life you can actually enjoy,” he says, rather than the healthiest life you can simply tolerate.

In fact, a study published in 2013 in Social and Personality Psychology Compass examined the degree to which healthy behaviors could impact health markers independent of weight loss. The researchers looked at the results from 21 previous diet studies, all of which included follow-up data for at least two years. In general, dieting did produce small changes in cholesterol levels, blood pressure, triglycerides, and fasting glucose level, but those changes didn’t correlate with the amount of weight participants lost, suggesting the weight loss was an unrelated byproduct of increasing healthy behaviors.

Interestingly, these researchers did find that weight loss did matter for some things, including the chances of being diagnosed with type 2 diabetes and needing to use diabetes medication. But Hunger explains that these findings were only based on two studies, including one from the Diabetes Prevention Program mentioned earlier.

In that case, “The intervention group only maintained about 8.8 pounds of weight loss at [the] final follow-up (about 4 percent initial body weight),” he explains. “If I were a betting man, I would say that any changes in diabetes incidence are not due to this very minimal weight loss but instead due to changes in health behaviors.”

The crucial reminder in all of this is that weight isn’t the only risk factor for any health condition. And losing weight isn’t the only treatment option.

Genetic, environment, and lifestyle factors all play a role in your risk for virtually every issue, and that includes factors like the level of social support you have, the amount of sleep you’re able to get, and life stressors—all of which need to be taken into account before creating any sort of treatment plan whether or not it incorporates weight goals.

For Dr. Freedhoff, creating that plan involves setting goals around increasing healthy behaviors rather than specific numbers or weights.

Doctors should be encouraging all of their patients to be active and maintain a balanced diet for the benefit of their overall health (while also recognizing that factors like time, financial resources, and abilities may affect their options). And, depending on a patient’s individual factors (weight, perhaps, being one of them), those behaviors may be even more important.

But your success, self-worth, or even your health don’t just come down to the numbers on a scale. Only you and your doctor know what makes sense for you.